Vestibular Changes Pre- and Post- Cochlear Implantation

Aim:
The profoundly deaf children referred for cochlear implantation may have vestibular dysfunction as part of their clinical presentation, or this function may be affected by the surgical procedure. The aim of this study is to describe and summarise the changes in vestibular status of children before and after cochlear implantation.

Hypothesis:
There have been some studies carried out in adults which have reported that cochlear implantation may affect the status of the vestibular function. We base our hypothesis to verify such effects on children. The null hypothesis for our study states that Cochlear implantation adversely affects balance status in a child.


Study Design:
Retrospective review of patient case-notes.

Methods:
Clinical records of 18 children were analysed. These children had had vestibular assessment before and after cochlear implant surgery. Details of audiovestibular clinical history and vestibular test findings before and after cochlear implantation were recorded. The change in vestibular status was ascertained on the basis of clinical assessment and change in directional preponderance pre and post cochlear implantation. Peak angular slow phase velocity was used in Jongkees formula to calculate the directional preponderance.

Results: 
There were 18 patients in the study (10 male, 8 female) with the mean age of implantation at 53 months. All patients had a unilateral cochlear implantation with their vestibular system assessed before and after surgery. One patient showed significant deterioration in her balance post implantation with afunction of vestibular organs towards the implanted side. 17 patients showed no difference in their balance status before and after cochlear implantation qualitatively. Comparison of directional preponderance pre and post implant surgery was inconclusive and failed to demonstrate a significant affect of surgery on the balance system. 

Conclusions:  Patient age, cause of deafness and preoperative testing were unable to predict who would develop a vestibular dysfunction post cochlear implantation in this study. Overall, cochlear implantation is found to be a safe option for profoundly deaf children. The incidence of significant balance disturbance as a result of cochlear implantation is much less in children than in adults. Most of the vestibular affects of surgery are temporary and compensate within a very short period of time. Further studies into susceptibilities of other vestibular end organs and the actual cause of trauma from implant surgery are necessary to fully understand the natural history of vestibular affects of cochlear implants.